How to end an outgoing phone call while connecting?

Question

So I try to make a app that will test if a phone can call phone numbers. And the main point is that when i push a call button and when the connection begins app ends a call and if there is no connection app shows an error. I managed to do a part where when button is clicked app calls a phone number but I can't come up with solution for ending a cal when there is connection (ringing). Is there any way to make this possible?

Button button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                String phone = "8686868686";
                Intent intent = new Intent(Intent.ACTION_CALL, Uri.fromParts("tel", phone, null));
                startActivity(intent);

                if (ActivityCompat.checkSelfPermission(MainActivity.this,
                        Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
                    return;
                }

                /*Context mContext = getApplicationContext();
                TelecomManager tm = (TelecomManager) mContext.getSystemService(Context.TELECOM_SERVICE);

                if (tm != null) {
                    boolean success = tm.endCall();
                    // success == true if call was terminated.
                }*/
            }
        });